The present invention relates to a bandwidth control device, a computer readable recording medium storing a program which are suitable for use in a packet communication network, and a method of controlling the bandwidth control device.
In a packet communication network, the limitation of a communication bandwidth is set to the interface of a terminal itself which is connected to the communication network. Moreover, a packet to be transmitted through the terminal is classified into any of a plurality of classes (for example, the uses of a packet) and the communication bandwidth is limited to a predetermined maximum value or less for each class or a communication bandwidth having a predetermined guaranteed bandwidth or more is maintained in many cases. For example, in Patent Document 1, there has been disclosed a technique for transmitting a packet while limiting a bandwidth for a plurality of classes. In the same document, first of all, a packet queue (the list of a packet to be transmitted sequentially) is created for each class of the packet. When a new packet is generated, a transmission scheduling time is determined corresponding to a class belonging to the same packet and the packet is added to the packet queue of the class together with the transmission scheduling time. Moreover, a prior transmission reserving queue and a non-prior transmission reserving queue which are shared by all of the classes are created and a packet output from each packet queue is sorted in order of a transmission scheduling time in the prior (or non-prior) transmission reserving queue. The packet stored in the prior transmission reserving queue is sequentially transmitted in order of the transmission scheduling time.
Patent Document 1: JP-A-2002-368799 Publication
According to the technique described in the Patent Document 1, however, each packet is transmitted after it is stored in two stages, that is, a packet queue for each class and a prior (or non-prior) transmission reserving queue. For this reason, there is a problem in that a memory capacity to be mounted on a terminal is increased and a control becomes complicated. Furthermore, there is a problem in that the limit value of the communication bandwidth of the whole interface of a terminal cannot be specified in the technique. More specifically, the limit value of the communication bandwidth of the whole interface is equal to the sum of the limit value of a communication bandwidth for each class. If the communication bandwidth of the whole interface is to be set to have a smaller value than the sum, it is necessary to further provide bandwidth control means for a leaky bucket in the latter stage of the prior (or non-prior) transmission reserving queue, and a required memory capacity is increased still more and a control becomes complicated still more.